In order to obtain uniform heating in a microwave oven, it is generally necessary to provide a wave spreader. In existing devices, a microwave oven generally comprises an enclosure in which a receptacle is disposed, one or more microwave sources disposed above the receptacle, and a wave spreader in the form of an antenna which is mounted to rotate between the microwave source and the inside of the receptacle. This type of spreader has the advantage of spreading the waves uniformly over the surface of the substance contained in the receptacle. However, the waves penetrate into the substance to be heated only to a limited depth such that when the receptacle contains a large quantity of substance to be heated, a portion of the substance is not reached by the waves.
The Applicant has already provided a solution to this problem, as described in French patent No. 2 588 063, by providing a microwave oven including means for stirring the substance contained in the receptacle, thereby causing all of the substance to be subjected to microwaves in order to obtain a uniform temperature of the substance inside the receptacle. However, homogenization can be obtained only insofar as the substance is stirred sufficiently to bring it regularly into a zone which is subjected to microwaves. In some cases, such stirring can be difficult, for example when the substance to be heated is fragile and must be stirred as gently as possible.
An object of the invention is to propose a microwave oven fitted with a wave spreader making it possible to make the temperature distribution inside the receptacle more uniform while minimizing the stirring to which the substance is subjected.